USB is a peripheral interface for attaching a wide variety of computing devices, such as personal computers, digital telephone lines, monitors, modems, mice, printers, scanners, game controllers, keyboards, storage devices, and/or the like. The specifications defining USB (e.g., Intel et al., Universal Serial Bus Specification, Revision 1.0, January 1996; updated as Revision 1.1 in September 1998; further updated as Revision 2.0 in April 2000; further updated as Revision 3.0 in November 2008; and further updated as “Universal Serial Bus 3.1 Specification, Revision 1.0” on Jul. 26, 2013, by Hewlett-Packard Company et al., and subsequent updates and modifications—hereinafter collectively referred to as the “USB Specifications,” which term can include future modifications and revisions) are non-proprietary and are managed by an open industry organization known as the USB Forum. The USB Specifications establish basic criteria that must be met in order for communication to comply with USB standards, and are incorporated herein in their entireties for all purposes. One of ordinary skill in the art will recognize many terms herein from the USB Specifications. Those terms are used herein in a similar manner to their use in the USB Specifications, unless otherwise stated.
Standards have been published that describe a universal serial bus (USB) Type-C connector, plug, and cable that can support communication via USB 2.0, SuperSpeed, and DisplayPort via the same connector, including concurrent communication of at least some of these signals. USB Type-C connectors, plugs, and cables are described in detail at least in “Universal Serial Bus Type-C Cable and Connector Specification, Revision 1.1,” released on Apr. 3, 2015, by USB 3.0 Promoter Group. Power delivery over USB and the negotiation thereof is described in detail at least in “Universal Serial Bus Power Delivery Specification, Revision 2.0, Version 1.1,” released on May 7, 2015, by Hewlett-Packard Company et al. DisplayPort communication is described in detail at least in “VESA DisplayPort Standard, Version 1.3,” released on Sep. 15, 2015, by VESA. Communication of DisplayPort information over a USB Type-C interface is described in detail at least in the VESA DisplayPort Alt Mode Standard, Version 1, released on Sep. 22, 2014, by VESA. Each of these documents and their contents are known to one of ordinary skill in the art, and are hereby incorporated by reference herein along with any earlier versions or related documents mentioned therein in their entireties for all purposes.
Techniques have been used to extend communication of video information over extension media, and also to extend communication of USB information over extension media. With the advent of USB Type-C connections and the incremental nature of their adoption, it is desirable to be able to connect a USB Type-C source or sink to a corresponding legacy sink or legacy source across an extension medium. However, problems arise when attempting to establish such connections across an extension medium. What is needed are techniques and devices for addressing these problems.